1. Technical Field
The present invention relates to light-emitting diode (LED) base structures each with an embedded capacitor, and more particularly, to an LED base structure equipped with an embedded capacitor and configured to use alternating current (AC) as a power source.
2. Description of Related Art
Development of light-emitting diode (LED) technology is swift and sophisticated. Also, LEDs have advantages, such as low volume, low power consumption, high reaction rate, long service life, and high vibration resistance. Hence, LEDs are gradually replacing traditional halogen lamps and fluorescent tubes and therefore have obviously become a new light source for use with future lighting devices.
LEDs are designed to glow when forward biased (electrically connected). In the situation where LEDs are driven by alternating current (AC) grid power, the LEDs give off light in intermittent bursts due to the periodicity of AC power. As a result, LEDs have rather limited application. At present, LEDs are powered mostly by direct current (DC) power sources.
Taiwan Patent No. I287607, entitled AC-powered LED Lighting Device and Light-emitting Unit of the Same, discloses an LED lighting device that uses AC power as a source of power supply, wherein the AC power has a forward voltage and a reverse voltage. The LED lighting device comprises a light-emitting unit. The light-emitting unit comprises a first LED chip and a second LED chip. The LED chips are connected in parallel and are electrically conductive in opposite directions. The forward voltage enables the first LED chip to be electrically conductive. The reverse voltage enables the second LED chip to be electrically conductive.
According to the aforesaid prior art, the two LED chips are connected in parallel and are electrically conductive in opposite directions. Hence, the two LED chips take turns giving off light when supplied with the AC power. Accordingly, the two LED chips can operate on AC power.
Referring to FIG. 1A, there is shown a graph of threshold voltage Vth against AC current when AC current is supplied to a conventional light-emitting diode (LED) base structure. To enable an LED to operate and give off light, it is necessary that the level of the voltage driving the LED is higher than the threshold voltage Vth of the LED. Hence, it takes a waiting period Tth for the driving voltage level to rise to the threshold voltage Vth in order to switch the voltage of AC power from one polarity to the other polarity and therefore enable the LED to give off light.
Referring to FIG. 1B, there is shown a sequence diagram of light emitted from an LED when AC current is supplied to the conventional LED base structure. A waiting period Tth intervenes between light emission periods T1, T2 of two light-emitting diodes LED1, LED2 in operation. Hence, if the light-emitting diodes LED1, LED2 take turns giving off light, the light emitted is intermittent and thus is flashing. As a result, the light-emitting diodes LED1, LED2 have rather limited application in an AC power environment.
Therefore, the conventional LED base structure is inconvenient and defective in terms of structure and use and thus has room for improvement. To solve the aforesaid problems, related manufacturers endeavor to find a solution. However, on the one hand, applicable designs have hitherto not been developed and finalized. On the other hand, general products lack an appropriate structure required for solving the aforesaid problems. Accordingly, it is imperative to develop a novel LED base structure with an embedded capacitor, which is not only an important R&D topic, but also a target which calls for urgent improvement to be made by the industrial sector.
In view of the existing drawbacks of the conventional LED base structure, the inventor of the present invention studied the conventional LED base structure with a view to making innovative improvement therein according to the inventor's years of experience and expertise of designing and manufacturing this product and by application of related theories, so as to develop a novel LED base structure with an embedded capacitor and thereby improve on the conventional LED base structure and render it more practical. Through continuous research, design, repeated trial production of samples and modification thereof, the inventor eventually created the present invention of high practicability.